JP2002524636A - Acoustic controllable open-cell polyolefin and method for producing the same - Google Patents

Abstract

(57) [Problem] To provide a foam excellent in sound absorbing performance. An expanded open-cell foam polymer composition comprising at least one linear or modified linear polyolefin, wherein at least 50% of the cells are open and the average size of the cells is at least 1 mm. Desirably, the sound absorption coefficient determined at 1,000 Hz by ASTM D1050 is greater than 0.15 and preferably has an air flow resistance of less than about 800,000 Rayls / m.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of foam materials suitable for sound absorbers in applications such as automobiles and tools.

[0002]

[Prior art and its problems]

Sound absorbing materials currently used in automobiles and tools have one or more disadvantages. For example, open cell polyurethane foam and melamine foam are thermoset materials, ie, crosslinked polymers, which are difficult to recycle. Also, polyurethane and melamine foams have poor hydrolytic stability when used in contact with water or when used for a long time in a humid environment. Shodies are relatively inexpensive fibrous pads that are typically made by chopping re-needles of thermoplastic or thermoset materials from waste. Shodies generally have good sound absorption, but are relatively dense and add significant weight to cars and tools.

[0003] Currently available open-cell polyolefin foams are not well suited as sound absorbers. For example, open-cell polyolefins made from cross-linked polyethylene are made by compression molding and are not suitable as sound absorbers from industrial sources. The pores of this foam are too small to provide adequate airflow and have poor sound absorbing properties. As a result, there is a need for recyclable thermoplastic foams with low cell density and open cells that exhibit excellent sound absorption for automotive and tool applications. In particular, it is desirable to provide a polyolefin foam that is substantially uncrosslinked or lightly crosslinked, has sufficient open cells and cell size sufficient to exhibit high porosity, and thereby exhibits excellent sound absorption.

[0004]

[Means for Solving the Problems]

The present invention relates to an expanded, open-cell, foamed polymer composition comprising at least one linear or modified linear polyolefin, wherein at least 50% of the cells are open and the average size of the cells is at least 1 mm. I will provide a. Desirably, the composition has a sound absorption coefficient measured at 1,000 Hz according to ASTM D1050 of greater than 0.15. Also in preferred foams, the composition has an airflow resistance of less than about 800,000 Rayls / m.

In a further aspect, the present invention is a soundproofing panel comprising two skin layers and a foam sheet disposed between the skin layers, wherein the foam sheet has an AST greater than 0.5.
Expanded with at least one linear or modified linear polyolefin having a sound absorption coefficient measured at 1,000 Hz according to MD1050, with at least 50% of the cells open and an average size of the cells of at least 1 mm Provided is a soundproof panel comprising an open-cell polymer composition. In another embodiment, the present invention relates to an ASTM D1050 compound comprising greater than 1
From an open-cell polymer composition having a sound absorption coefficient measured at 2,000 Hz and comprising at least one linear or modified linear polyolefin, wherein at least 50% of the cells are open and the average size of the cells is at least 1 mm. The present invention provides a foam sheet characterized in that:

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

Not all open-celled polyolefin foams are suitable as sound absorbers. It is known that open cell foams having relatively low airflow resistance are suitable for sound absorption. Low airflow resistance generally requires relatively large holes on the bubble wall.
It is generally difficult to make open cell foams having large pores on the cell walls from common foam resins such as low density branched polyethylene resins. This is because bubbles start to disappear as soon as holes are formed in the cell walls in the process of producing the resin foam.
There is no known example that provides guidance on how to make a foamed material having large pores from a polyolefin resin.

[0007] It has been found that stable open cell foams having relatively large cells and sufficiently absorbing sound can be readily produced from linear polyolefin compositions. It is believed that this foam has relatively large cell windows, so that relatively large pores are provided therein. Suitable polyolefin resins for the production of open cell foams having large cells include linear polyolefins, modified linear polyolefins or blends of linear polyolefins or modified linear polyolefins with other polyolefins having a melting point at least about 10 ° C. lower than them. Things are included. In the case of a blend of a linear or modified linear polyolefin and a polyolefin having a melting point lower by at least about 10 ° C. than the linear or modified linear polyolefin, the low melting point polymer becomes an initial site for opening the cell wall and forms a cell wall. It is believed that it will remain fluid for a longer time, thereby promoting the formation of larger pores. It has also been found that blending a polyolefin resin with a low-melting-point polyolefin elastomer improves the sound absorbing performance of the foam obtained.

[0008] The foam material of the present invention is made from a polymer composition comprising at least one linear or modified linear polyolefin made using a Ziegler-Natta or metallocene catalyst. Examples of the linear or modified linear polyolefin include homopolymers of C _{2 to} C ₂₀ olefins such as ethylene, propylene and 4-methyl-1-pentene, and ethylene and at least one C _{3 to} C ₂₀ α-olefin. There are copolymers or copolymers of propylene with ethylene and / or C ₄ -C ₂₀ α-olefins. Preferred monomers are C ₂ -C ₁₀ α-olefins, especially ethylene, propylene,
There are isobutene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene. Among these polyolefin resins, a polypropylene homopolymer or an ethylene-propylene copolymer is preferred.

As used herein, the term “modified linear polyolefin” refers to a linear polyolefin having some long-chain branching due to expansion of a foam. A preferred modified linear polyolefin is high melt strength (HMS) polypropylene, which can be made by irradiating linear polypropylene. HMP-PP is disclosed in U.S. Pat. No. 4,916,198. These linear or modified linear resins can be blended with another polyolefin whose melting point is at least 10 ° C. lower than these linear or modified linear polyolefins. As this low melting point polyolefin, a substantially linear polyolefin prepared using a constrained geometry catalyst is preferred.

[0010] Preferred substantially linear polyolefins are made using a constrained geometry catalyst as described in US Patent No. 5,272,236. Preferred substantially linear polyolefins are homopolymers of ethylene or copolymers of ethylene and α-olefins or styrene and have a melt index (MI) of from about 0.01 to about 1,000 g / 10 minutes. As used herein, the term "substantially linear polyolefin" refers to a polyolefin in which the main chain of the polymer is not substituted or substituted with three or less long-chain branches per 1,000 carbon atoms. Preferred polymers are substituted with about 0.01 to about 3, more preferably about 0.01 to about 1, and even more preferably about 0.3 to about 1, long chain branches per 1,000 carbon atoms. Is what it is.

Preferred substantially linear polyolefins include homopolymers of propylene and copolymers of propylene with an ethylenically unsaturated comonomer copolymerizable with propylene. These propylene polymer materials include one or more propylene homopolymers alone, one or more propylene copolymers, a blend of any one or more propylene homopolymers and copolymers, or a blend of these with a non-propylene polymer. There is. These propylene polymer materials preferably have more than 50% by weight, especially more than 70% by weight, of propylene monomer units. Preferred monoethylenically unsaturated comonomers include α-olefins. Most preferably, the propylene copolymer has an ethylenically unsaturated comonomer content of less than about 20% by weight, ie, more than 80% by weight, of the propylene monomer.

Particularly useful propylene copolymers are copolymers of propylene with one or more non-propylene olefins. The propylene copolymer is random and block copolymers of an olefin selected from the group consisting of propylene with ethylene and C ₄ -C ₁₀ alpha-olefin. Propylene copolymers also include random terpolymers of propylene with an α-olefin selected from the group consisting of ethylene and C ₄ -C ₈ α-olefins. For terpolymers having both ethylene and C ₄ -C ₁₀ α-olefins, the ethylene content is preferably 20% by weight or less. C ₄ -C ₁₀ α-olefins include, for example, 1-butene, isobutylene, 1-pentene,
There are linear or branched C ₄ -C ₁₀ α-olefins such as methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene.

The polymer blends of the present invention preferably comprise at least 50%, more preferably at least 60%, by weight of the linear or modified linear polyolefin and the balance preferably other olefin polymers, most preferably at least 50%, by weight of the blend. Preferably, it is composed of a substantially linear polyolefin. Other preferred polyolefins that can be blended with the linear or modified linear polyolefin include high, medium and low density polyethylene, polybutene-1, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene rubber,
There are styrene-butadiene rubber, ethylene-ethyl acrylate copolymer and the like. Preferably, the polyolefin foam of the present invention can be easily recycled. Therefore, it is desirable that the polymer composition used for producing the sound absorbing foam of the present invention does not contain a crosslinkable polymer and / or a crosslinking agent. Preferably, the resulting sound absorbing foam material is substantially non-crosslinked. However, "non-crosslinked" as used herein includes slight crosslinks that can occur naturally without the use of a crosslinking agent, and "substantially noncrosslinked" is described in U.S. Patent No. 5,348,795. And light-crosslinked polymers as described above.

In the production of the sound-absorbing foamed material of the present invention, a general method is used in which a linear or modified linear polyolefin resin or a resin blend containing these is supplied to a well-known melt processing device such as an extruder, melted, and measured. Is melted in a simple manner. A blowing agent is mixed under pressure with the polymer resin or polymer resin blend to form a flowable gel or mixture. Extrusion of the flowable gel or mixture through the die opening of the extruder into the low pressure region activates the blowing agent and expands the polymer blend into a foamed structure. 16
0 kg / m ³ or less, more preferably 80 kg / m ³ or less, most preferably 40 k
A foam having a density of not more than g / m ³ can be obtained. The foam is at least 50% open-cell or open-cell. Average bubble size is about 1 to about 8mm
, More preferably from about 1.5 to about 5 mm.

[0015] Blowing agents that can be used include physical or chemical blowing agents. However, physical blowing agents are preferred. Examples of physical blowing agents include C1-9 aliphatic hydrocarbons, C1-4 halogenated aliphatic hydrocarbons and C1-3 aliphatic alcohols. Examples of the aliphatic hydrocarbon include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane and the like. Of the halogenated hydrocarbons, fluorinated hydrocarbons are preferred. Examples of the fluorinated hydrocarbon include methyl fluoride, perfluoromethane, ethyl fluoride, 1,1-difluoroethane (HFC-152a), 1,1,1-trifluoroethane (HGC-143).
a), 1,1,1,2-tetrafluoroethane (HFC-134a), pentafluoroethane, perfluoroethane, 2,2-difluoropropane, 1,1,1
-There are trifluoropropane, perfluoropropane, perfluorobutane and perfluorocyclobutane.

Examples of the partially halogenated chlorocarbon and chlorofluorocarbon used in the present invention include methyl chloride, methylene chloride, ethyl chloride, 1,1-dichloroethane, 1,1-
Dichloro-1-fluoroethane (HCFC-141b), 1-chloro-1,1-
There are difluoroethane (HCFC-142b), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124). . Examples of fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), and trichlorotrifluoroethane (CFC-1).
13), dichlorotetrafluoroethane (CFC-141), chlorohexafluoropropane and dichlorohexafluoropropane. Fully halogenated chlorofluorocarbons are not preferred because they have ozone destructive properties. A more preferred organic blowing agent is a mixture of HCFC-142b and ethyl chloride.

These blowing agents may contain one or more inorganic or chemical blowing agents as minor components (up to 15% by weight). Examples of inorganic blowing agents useful for making the foams of the present invention include carbon dioxide, argon, water, air, nitrogen and helium. Examples of chemical blowing agents include azodicarbonamide, azodiisobutyronitrile, benzenesulfonhydrazide, 4,4-oxybenzenesulfonylsemicarbonamide,
Azodiisobutyronitrile, benzenesulfonhydrazide, 4,4-oxybenzenesulfonylsemicarbazide, p-toluenesulfonylsemicarbazide, barium azodicarboxylate, N, N'-dimethyl-N, N'-dinitrosoterephthalamide and trihydrazino There is a triazine.

The amount of blowing agent added to the polymer melt to form a foam-forming polymer gel is preferably from about 0.5 to about 5 g per kg of polymer, more preferably from about 0.8 to about 5 g per kg of polymer.
It is about 4 g. While substantially non-crosslinked foams are preferred, lightly crosslinked foams can also be made with the present invention. These lightly crosslinked foams are not as easily recyclable as the preferred substantially non-crosslinked foams, but otherwise usually have the same advantages: low density, good sound absorption, and good structural integrity. These compositions may contain one or more crosslinkable polymers. Crosslinkable polymers include copolymers of ethylenically unsaturated monomers or other olefinic monomers with ethylenically unsaturated monomers having carboxylic acid functions, hydroxyl groups, or amine or amide groups. These monomers can be suitably attached to the copolymer, for example, as a random copolymer, as a block or sequenced copolymer, or as a graft copolymer. These materials and the methods themselves are known. As the crosslinkable polymer in the blend, a copolymer of ethylene and acrylic acid is preferable. Examples of crosslinkers useful in making crosslinked foams include epoxy and amino functional silanes, organofunctional alkoxysilanes, multi-epoxy functional resins, titanates and amines. These crosslinkers react with the crosslinkable polymer of the blend to form a lightly crosslinked foam. Light cross-linking of the polymer blend improves melt strength and makes continuous foam extrusion in conventional melt processing equipment easier.

The amount of the crosslinkable polymer is preferably at most 70%, more preferably at most 60%, most preferably at most 50% of the weight of the resin blend. Some of the available cross-linking agents form cross-links through reactions that release alcohol. For example, an alkoxy-functional silane crosslinker is grafted onto an ethylenic polymer containing carboxylic acid groups to form an acyloxysilane linkage while releasing the alcohol. Similarly, amino and epoxy-functional silanes release alcohols and graft onto polymers with carboxylic acid or anhydride groups. The presence of an alcohol in the foam extrusion line can control the crosslinking reaction and effectively retard crosslinking until the polymer blend exits the extrusion die.

A preferred silane crosslinker has the general formula: RR'SiY _2, where R represents an epoxy or amine function linked to silicon via a silicon carbon bond, which is a carbon,
Y, consisting of hydrogen and optionally oxygen or nitrogen, is a hydrolysable organic group, R '
Is a hydrocarbon group). In addition the general formula: R _a S
i (O′R) _b (where a is 1 or 2, b is 2 or 3, R is a methyl group or an organic reactive alkyl group, and OR ′ is a hydrolyzable alkoxy group)
Is also a preferred silane. Preferred multi-epoxy functional resins include epoxy novolak resins, specific examples of which are commercially available from The Dow Chemical Company.
E. FIG. N. 431. These multi-epoxy functional resins have a plurality of epoxy-functional reaction sites that can react with carboxylic acid functions on the crosslinkable polymer.

Preferred titanate crosslinking agents include the general formula: Ti (OR) ₄ (where R is 1 carbon atom)
Or an alkyl group represented by the general formula: (R
O) _m Ti (O—X—R ₂ —Y) _n (where R is an alkyl group, X is carbonyl, R ₂ is a long-chain carbon atom, and Y is a reactive double bond or amino And m and n are total integers of 4).
Most preferred titanate coupling agents are titanium isopropoxide and tetramethyl titanate. The titanate crosslinker releases an alcohol to react with the carboxylic acid or hydroxyl functionality on the crosslinkable polymer.

Preferred amino crosslinkers include hexamethoxymethyl melamine (HMMM) and alkylated glycol lariformaldehyde resins. Amino crosslinkers react with hydroxyl, carboxylic acid or amide functional groups on the crosslinkable polymer. The crosslinker is added to the polymer gel blend along with the blowing agent and reacts with the crosslinkable polymer component of the blend. Crosslinking increases the melt strength and melt viscosity of the gel, but leaves the polymer fluid. Some crosslinking agents form alcohols as a result of the crosslinking reaction, limiting the degree of crosslinking. However, also in this case, the alcohol diffuses into the gas phase together with the volatile foaming agent, so that the crosslinking reaction proceeds during expansion of the foam at the die exit. If desired, alcohol may be added to the blowing agent to further control the crosslinking reaction. Preferred alcohols are those having a low molecular weight having 1 to 4 carbon atoms such as methanol, ethanol, isopropanol and butanol.

The crosslinkable polymer that can be used in the present invention can also be prepared using a free radical generating compound. For example, linear low density polyethylene can be lightly crosslinked using an organic peroxide such as dicumyl peroxide. Also, polypropylene can be crosslinked using multi-azide functional compounds. The foam product of the present invention can be produced using a general melt processing apparatus such as continuous extrusion from a screw type extruder. These extruders typically have a series of continuous zones with a feed zone, a compression and melting zone and a metering zone and a mixing zone. The barrel of the extruder is equipped with a common electric heater for separate temperature control.

An inlet is provided for adding a mixture of a fluid blowing agent and optionally a cross-linking agent under pressure to the polymer blend in the extruder barrel between the metering zone and the mixing zone. If desired, the crosslinking agent is pumped in a controlled manner into the fluid blowing agent stream upstream of the injection nozzle. The blowing agent and the desired crosslinking agent are kneaded by conventional means into the starting polymer to form, preferably continuously, a flowable gel or mixture. In the mixing zone of the extruder, the polymer blend, the foaming agent, and the crosslinking agent of the desired component are heated to plasticize the polymer resin and pressurized to keep the foaming agent in a liquid state, and a mechanical action to achieve sufficient mixing. And are combined.

The discharge end of the mixing zone of the extruder is connected to a die orifice via a cooling and temperature control zone. The hot polymer gel is cooled and transferred through the die orifice to a low pressure region (eg, normal outside air pressure) where the blowing agent is activated and the polymer gel expands to a low density foam. Once the foamed extrudate has formed, it is released from the die, cooled and cured. The foam extrudate can be formed as a slab, tube, sheet, or the like. It is desirable to add common fine solid materials such as talc, calcium silicate, zinc stearate, etc. to the polymer gel prior to extrusion. These finely divided solid materials help control the size of the cells and are usually used in amounts of up to 5% by weight of the polymer. As in the prior art, many fillers, pigments, lubricants, antioxidants and the like are added as desired.

In accordance with a preferred embodiment of the present invention, the foam may be softened after extrusion and mechanically compressed to increase open cells. The foam of the present invention is useful as a sound absorbing material and a sound insulating material. The foam is characterized by an open cell content of 50% or more and a cell size of more than 1 mm. Preferably the open cell content is at least 70%, the cell size is at least 1.5 mm,
The compressive strength is 30 kPa or more with a deviation of 10%. The foam is preferably 1,0
Sound absorption coefficient (s) greater than 0.15 at 00 Hz, more preferably greater than 0.2
has an underabsorption coefficient.

The foam of the present invention can be made to have an appropriate cross-sectional size or structure, and is particularly suitable for making a foam sheet. When used as a sound absorbing material, the pore density of the foam is preferably 1 or more per 10 cm ² , more preferably 1 or more per 5 cm ² ,
Most preferably, it is preferable to form one or more holes per 1 cm ² . When used as a decoupler, the foam should be 50% or more, more preferably 8% or more.
0% or more pre-compressed, and the compression strength is 30 kPa or less, preferably 2%, with a deviation of 10%.
It is preferably set to 0 kPa or less, most preferably 10 kPa or less. When the foam of the present invention is used for sound control end use, the air flow resistance is about 800,
It is preferably lower than 000 Rayls / m (800,000 Pa · s / m ² ). In particular, an air flow resistance of 100,000 Rayls / m (100,000 Pa · s / m ² ) or less, more preferably 50,000 Rayls / m (50,000 Pa · s / m ² ) or less is more preferable depending on the final use of the foam.

FIG. 7 shows a cross section of a soundproof panel 10, such as a soundproof automobile door panel, having a first skin layer 12, a second skin layer 14, and a soundproof insert 20. Soundproof insert 2
0 has an open cell content of at least 50%, a cell size of at least 1 mm,
1 is a foam sheet of the present invention made from a linear or modified linear polyolefin or a blend containing the same. The foam insert 20 has low dynamic stiffness to effectively reduce the transfer of sound or vibration through the structure.
ss). For example, one of the skin layers 12 may be sheet metal and the other skin layer 14 may be a highly filled ethylene vinyl acetate copolymer or a thermoplastic elastomer. Panel 20 may act as a sound absorber, a sound insulator, or a sound / vibration decoupler. Current,
Open cell polyurethane foam or fiber bats are commonly used as decouplers. Polyurethane foams are difficult to recycle and are not suitable for use in wet environments.

[0029]

The following examples illustrate the invention but do not limit the scope of the invention. In these, parts and percentages are indicated by weight unless otherwise specified. Example 1 The equipment used in this example is a 38 mm (1-1 / 2 inch) screw extruder with an additional zone of mixing and cooling at the end of the usual continuous zone of feeding, metering and mixing. There is an opening for the blowing agent on the extruder barrel between the metering and mixing zones. There is a die orifice with a rectangular opening at the end of the cooling zone. The height of this opening (hereinafter referred to as the die gap) is adjustable and its width is fixed at 6.35 mm (0.25 inch). In this example, a high melt strength (HMS) polypropylene resin blended with a polyolefin elastomer (POE) resin was extruded into an open cell foam.

The resin blend has an HMS 96.8 / 3.2 propylene / ethylene copolymer resin having a melt flow rate (MFR) of about 2 and a MFR of about 0.3 as measured at 230 ° C./2.16 kg by ASTM D1238. It is a 50/50 weight ratio blend with a common polypropylene homopolymer resin. HMS polypropylene resin had an MFR of about 0.6. The POE resin is Dow ENGAGE ™ resin EG8150 having a melt index of 0.5 and a density of 0.870 g / cm ³ measured at 190 ° C./2.161 kg according to ASTM D1235. The POE resin was made using INSITE ™ technology catalyst (constrained geometry catalyst). In practice, the particulate polyolefin resin was pre-blended in a predetermined ratio and with an antioxidant package and a small amount of talc powder for limiting cell size. The talc powder concentration is 0.015 parts per 100 parts (pph) of polymer.

The antioxidant package includes Irganox ™ 1010 hindered phenolic antioxidant from Ciba Geigy and Uttranox from General Electric.
(Trademark) 626 phosphite type antioxidants each consisting of 0.1 pph.
The antioxidant was used by kneading the polyethylene resin in a concentrated form at a concentration of about 10%. This solid mixture was then fed to the hopper of the extruder and fed to 5.44 kg / hr (12 lb / hr).
Extruded at a uniform ratio. The temperatures maintained in the extrusion zone were 188 ° C in the feed zone, 196 ° C in the transition zone, 210 ° C in the melting zone, 216 ° C in the metering zone, and 213 ° C in the mixing zone. Isobutane was injected into the inlet at a uniform rate such that the foaming agent concentration was about 1.7 g-mol / kg polymer. The temperature of the cooling zone was gradually reduced to cool the polymer / blowing agent mixture (gel) to the maximum temperature of each formulation that provided excellent open cell foam. The foaming temperature for tests 1.2 and 1.3 was 154 ° C., and the die temperature was kept approximately the same as the foamable gel temperature. The die opening was adjusted to obtain a good foam strand without prefoaming.

An excellent foam having a width of about 34 mm and a thickness of about 11 mm was obtained with a die opening size of about 0.9 mm. As shown in Table 1, the foam was a low density, substantially open cell structure with an open cell content greater than 75%. The bubble size measured in the horizontal direction is 1.
It was relatively large, ranging from 6 mm to 2.3 mm. About one month after extrusion, the foam was subjected to other tests, i.e., determination of heat distortion temperature, tensile strength and compressive strength.

[0033] Physical and mechanical properties of the foam: The test results are summarized in Table 1. The heat distortion temperature of PP / POE blend foam is P
20 ° C. lower than P foam (150 ° C.), but high enough for many applications, including automotive applications. The POE resin had a desirable effect on the physical properties of the foam. The POE resin made the foam tougher and softer. The PP / POE blend foam extended more than twice as much as the PP foam. As expected from the low modulus of the POE resin, the PP / POE blend foam had much lower compressive strength than the PP foam. During the initial compression test, the foam pieces were compressed to about 80% deviation. After compression, the foam pieces returned to substantially their original thickness. The test piece was subjected to another compression test to record the compression strength. The foam softened during the first compression, as evidenced by the compressive strength data during the second compression shown in Table 1. Deviation 1
The compressive strength at 0% was reduced by a factor of seven. Low compressive strength or low compressive modulus with low deviation is desirable as a soundproofing material.

[0034]

[Table 1]

The sound control properties of the foam made in Example 1 The selected foam made in Example 1 was tested for sound absorption performance. PP foam and 60/40 PP / POE foam were selected. The foam strands were shaved off and united to form 12.7 mm thick test specimens. The foam piece was subjected to an ASTM E1050 sound absorption test. The sound absorption coefficient was determined as a function of frequency for two test pieces per foam. The average of the two test results was calculated and is shown in FIG. Table 2 shows the sound absorption data at the selected frequency together with the data of the foams produced in Example 2 and Reference Example. These foams absorbed sound energy well. PP / POE blended foam has a P
Absorbed sound better than P foam.

[0036]

[Table 2]

Example 2 The foaming device used in this example has essentially the same configuration as that used in Example 1.
mm (3 to 1/2 inch)-Screw type extruder. 57.2 mm (2.2
A 5 inch (5 inch) die gap adjustable slit die was fitted to the device. In practice, a linear low-density polyethylene (Dowlex 2038 manufactured by The Dow Chemical Company, melt index 1.0, density 0.935 g / cm ³⁾
) And a low-density branched polyethylene (density 0.923 g / cm ³ , melt index 0.7) blend of about 50 lb / hr (250 lb / hr)
At an even rate. Further, 1.2 pph of stearyl stearamide and 0.025 pph of dibutyltin dilaurate (all in a concentrated form) were also supplied together with the polymer. Stearyl stearamide was added to improve the dimensional stability of the foam and dibutyltin dilaurate was added as a catalyst for the silane crosslinking reaction. The feed, transfer, melting and metering zones of the extruder were set at 150 to 200 ° C. to uniformly melt and extrude the polymer. Approximately 20 pp of CFC-12 blowing agent in the mixing zone maintained at 230 ° C.
h. Add azido-functional silane (Hercules C) to the blowing agent injection stream
Az-CupMC manufactured by corporation (98 persons) was injected at a rate of 0.2 pph. The gel was cooled to the optimum foaming temperature by adjusting the cooling zone temperature. About 115 ° C
Excellent open cell foam was obtained at the gel temperature of With a die opening adjusted to suppress prefoaming, a thickness of about 30 mm and a width of 200 m
m was obtained. This foam has a density of about 27 kg / m ³ and a cell size of 1.
2 mm, 89% open cell content. The foam was soft with a deviation strength of 25% and a compressive strength of about 25 kPa.

The extruded slab was sliced into 0.5 inch (12.7 mm) thick sheets and compression tested through two drive rolls with a gap adjusted to about 10% of the foam thickness. The compressed foam had an open cell content of 90% and a compressive strength of 16 kPa with a deviation of 25%. The foam already had a high open cell content upon extrusion and further open celling was minimal. Both the as-extruded and compressed foam pieces are ASTM E1050
It was subjected to a sound absorption test. As shown in FIG. 2 and Table 2, sound energy was sufficiently absorbed at high frequencies from both foam pieces. With respect to sound absorption, foam compression does not improve performance. However, compression-softened foams have lower dynamic stiffness and provide improved soundproofing, for example, against impact noise.

Comparative Example 1: The foaming apparatus used in this example is the same as that used in Example 2 except for the die orifice. The die has the same configuration as used in Example 2, but has a width of 25.4 mm (1
Inches) and narrow. In this example test, a high melt strength (HMS) 2/98 ethylene / propylene random copolymer having a melt flow rate of 0.43 (230 ° C./2.16 kg according to ASTM D1238) was used for foam expansion. In practice, the particulate polypropylene was fed to the extruder at a uniform rate of about 136 kg / hr (300 lb / hr). A small amount of talcum powder (0.1 pph) was also added for cell size control and Irganox 1010 (Ciba Geigy) and Ultranx as antioxidant concentrates.
ox (General Electric) was added to a concentration of 0.1 ppm. The temperatures maintained in the extruder zone were about 130 ° C in the feed zone, 200 ° C in the melting zone, 230 ° C in the metering zone, and 210 ° C in the mixing zone. HCFC-142b blowing agent was injected under pressure into the mixing zone at a rate of 1.5 g-mol / kg polymer. The polymer / blowing agent mixture was cooled to an optimum foaming temperature of about 154 ° C and the die gap was adjusted to create a foam without prefoaming. 2.2
An excellent foam having a thickness of 43 mm and a width of 123 mm was obtained with a die gap of 0.088 inch (mm).

The foam was dimensionally stable during aging at room temperature (about 20-23 ° C.).
A foam aged sufficiently for one month or more has a density of 24.2 kg / m ³ (1.51 p.
cf), the cell size was 0.9 mm, and the open cell content was 35%. The foam was cut into sheets about 12.7 mm thick. Some of the sheets were compressed to 90% of their thickness by the method described in Example 2. Bubbles were broken by this compression. The open cell content of the foam is increased to 95% and the compressive strength at a deviation of 25% is increased from about 84 kPa to 26
kPa. The as-extruded and compressed foam sheets were subjected to ASTM E1050.
It was subjected to a sound absorption test. As shown in FIG. 3 and Table 2, the co-foams, independent of their open cell content,
It has been shown to be undesirable as a sound energy absorber. The foam with a cell size of 0.9 mm was significantly inferior to the foam made in Test 1.1 with a cell size of 2 mm. Even when the open cell content is increased to 95%, compression has little effect on the sound control performance of the foam.

Comparative Example 2: The apparatus used in this example is the same as that used in Example 32 except for the orifice die. 0-diameter arranged in 18 rows and 112 steps in the same square pattern with 0.25 inches between openings
. A perforated die with 2016 openings of 041 inches was mounted on the device. The operation of this device is essentially the same as in Example 3. In this example, a melt flow rate of 0.34 (230 according to ASTM D1238)
C./2.16 kg) using a HMS2 / 98 ethylene / propylene random copolymer. A small amount of talcum powder (for controlling the bubble size)
0.05 pph) and 0.2 pph of the antioxidant. The antioxidant consisted of 50% of a hindered phenol type antioxidant (manufactured by Ciba Geigy) of 1010 Irganox and 50% of a phosphite type antioxidant (manufactured by Borg Warner Chemical) of Ultranox name.

The antioxidant was preliminarily kneaded into a master batch using a base resin. This solid mixture was fed to the extruder at a uniform rate of about 181 kg / hr (400 lb / hr). The temperature maintained in the extruder was about 130 ° C in the feed zone, 200 ° C in the melting zone, and 2 ° C in the metering zone.
The temperature was 30 ° C and 210 ° C in the mixing zone. HCFC-142b blowing agent was fed to the mixing zone under pressure at a rate of 35.8 kg / hr (79 lb / hr, which corresponds to 19.8 pph or about 2.0 g-mol / kg polymer). The homogeneous mixture of polymer and blowing agent was cooled to about 154 ° C. to obtain an excellent foam with fine cell size. The foam strands adhered to each other to form a foam slab filled with most voids. The cross-sectional size of the foam is about 61
mm × 605 mm.

This foam showed little dimensional change (1% or less) during aging and exhibited excellent dimensional stability. Two weeks after extrusion, the properties of the foam were examined.
It had 3.7 kg / m ³ , a cell size of 0.58 mm and an open cell content of 69%. This foam had a vertical compressive strength of about 49 kPa with a deviation of 25%. The foam slab was cut into 25.4 mm thick sheets and compressed 90% as described in Example 2. The compact had a higher open cell content of 94% and a lower compressive strength of 17 kPa compared to the as-extruded foam. A 25.4 mm thick piece of foam was tested for sound absorption performance. As shown in FIG. 4 and Table 2, the foam pieces exhibited poor sound absorption performance independent of the open cell content. Even if the thickness of this foam piece was twice that of the foam made in test 1.1, the sound absorption performance was inferior to that of test 1.1.

[0044]

[Table 3]

Example 3 The foaming apparatus used in this example was the same as that used in Example 2 except for the die orifice, except that an annular sheet die and a sizing mandrel fitted to it were fitted. The diameter of the annular orifice is 2 inches and the gap of the annular body is adjustable. The sizing mandrel attached to the die orifice has a diameter of 210 mm (8.25 inches). In this example, an open cell sheet foam was made from the same polymer blend used in Test 1.2 of Example 1 of a 70/30 blend of HMS polypropylene resin and POE resin. An about 5 mm thick foam sheet was subjected to test 3.1 and tested for about 10
The mm-thick foam sheet was subjected to test 3.2. In operation, a particulate blend of polypropylene resin and POE resin was tested at 136 kg / hr (300 lb / hr) in Test 1.1 and 182 k / hr in Test 3.2.
Feed to the extruder at a uniform rate of g / hr (400 lb / hr). Also supplied was 0.03 pph of talcum powder and 0.25 pph of the same antioxidant used in Example 1. The temperature maintained in the extruder zone was about 130 ° C in the feed zone, 200 ° C in the melting zone, and 250 ° C in the metering zone.
° C and 195 ° C in the mixing zone.

Isobutane was injected into the mixing zone at a rate of 10 pph (1.72 g-mol / kg polymer). The cooling zone and the temperature of the die were lowered to obtain an excellent open cell foam. The temperatures were 158 ° C and 156 ° C in test 3.1 and 154 ° C and 156 ° C in test 3.2. The annular orifice gap was adjusted to produce a foam without prefoaming. The foamable gel was pulled out from the size mandrel to obtain a tubular foam. This tubular foam was cut into an average sheet, passed through a set of pulling rolls and wound on rolls. The thickness of the foam sheet was adjusted by the die gap and the drawing speed. Withdrawal speed is about 23m / min in test 3.1,
In test 3.2, it was 20 m / min. Excellent quality foam sheets with high open cell content were obtained in both tests. After testing the physical and mechanical properties of these foams, they were tested for sound absorption.
The sound absorption test was performed on both the extrudate and the sample piece after drilling according to ASTM E1050 using an impedance tube. The sheet was perforated with a 2 mm diameter needle in a 10 mm × 10 mm square pattern.

Physical and Mechanical Properties of Sheet Foam: The properties of the sheet foam made in this example are shown in Table 3. This sheet foam had a high open cell content and a high heat distortion temperature. The compressive strength was low, similar to those foams that underwent the compression of Example 1. The low compressive strength is due to both the orientation of the foam in the extrusion direction and the partial compression that the foam undergoes as they move through the pull roll.
These low modulus open cell foams with high heat distortion temperatures are useful for automotive sound absorption. This sheet foam may, for example, provide a break (de) between the sheet metal and the heavy layer.
Useful for coupling inserts.

[0048]

[Table 4]

Sound Absorption Characteristics of Sheet Foam: Table 4 and FIGS. 5 and 6 show the sound absorption characteristics of the sheet foam. At medium and high frequencies, these sheet foams absorb sound well. Drilling generally improves the sound absorption by the sheet foam. Their sound absorbing performance with relatively thin materials is satisfactory.

[0050]

[Table 5]

Although the foams and methods of the present invention have been described in detail for one example, it will be understood that variations may be made within this range without altering the essence of the present invention according to the manufacturer's manufacturing process and intentions.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the sound absorption coefficient and the frequency of the foam of Example 1.

FIG. 2 is a graph showing the relationship between the sound absorption coefficient and the frequency of the foam of Example 2.

FIG. 3 is a graph showing the relationship between the sound absorption coefficient and the frequency of the foam of Comparative Example 1.

FIG. 4 is a graph showing the relationship between the sound absorption coefficient and the frequency of the foam of Comparative Example 2.

FIG. 5 is a graph showing the relationship between the sound absorption coefficient and the frequency of the foam of Example 3.

FIG. 6 is a graph showing the relationship between the sound absorption coefficient and the frequency of the foam of Example 3.

FIG. 7 is a schematic sectional view of a soundproof panel.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] August 31, 2000 (2000.8.31)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR , BY, CA, CH, CN, CZ, DE, DK, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP , KE, KG, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, YU, ZA, ZWF Term (reference) 4F074 AA16 AA17 AA21 AA24 AA25 AA28 AA98 AB03 AB05 BA38 BB02 BB22 BB28 CA22 CC04Y CC05Z CC06X DA02 DA03 DA19 DA57 4J002 BB00W BB00X BB03W BB05W BB12W BB15W BB15X BB20Y GR00

Claims (30)

[Claims] 1. A method comprising: at least one linear or modified linear polyolefin;
At least 50% of the bubbles are open and the average size of the bubbles is at least 1
mm. Expanded open cell foam polymer composition, characterized in that 2. The composition according to ASTM D1050, wherein the composition is greater than 0.15.
The composition of claim 1 having a sound absorption coefficient measured at 2,000 Hz. 3. The composition of claim 1, wherein the composition has an airflow resistance of less than about 800,000 Rayls / m. 4. The expanded foam of claim 1 wherein the linear or modified linear polyolefin is a homopolymer or copolymer of ethylene or propylene. 5. The method according to claim 1, wherein the linear or modified linear polyolefin is ethylene and at least one
Expanded foam of claim 1 which is C ₃ -C ₂₀ alpha-olefins copolymers. 6. The expanded foam of claim 1 wherein the linear or modified linear polyolefin is a copolymer of propylene and at least one α-olefin selected from ethylene and a C ₄ -C ₂₀ α-olefin. 7. The expanded foam of claim 1 wherein the linear or modified linear polyolefin is a linear low density polyethylene. 8. The expanded foam of claim 1 wherein the linear or modified linear polyolefin is a high melt strength modified polypropylene. 9. The expanded foam of claim 1 wherein the polymer composition further comprises a second additional polyolefin. 10. The composition of claim 10, wherein the second polyolefin is 50% of the total polymer weight of the composition.
10. The expanded foam of claim 9 in an amount less than weight percent. 11. The expanded foam of claim 9, wherein the second polyolefin is less than 40% by weight of the total weight of the composition. 12. The foam according to claim 1, wherein the foam has a density of less than 160 kg / m ^3.
Expanded foam. 13. The expanded foam of claim 1 wherein the foam has a density of less than 80 kg / m ³ . 14. The expanded foam of claim 1 wherein the foam has a density of less than 40 kg / m ³ . 15. The expanded foam of claim 1 wherein the average cell size is at least 1.5 mm. 16. The expanded foam of claim 1 wherein the average foam size is at least 2 mm. 17. The expanded foam of claim 1, wherein at least 70% of the cells are open cells. 18. The expanded foam of claim 1, wherein at least 85% of the cells are open cells. 19. The expanded foam of claim 9 wherein the second polyolefin is a substantially linear polyolefin. 20. The expanded foam of claim 1 wherein the foam is extruded in sheet form. 21. The polymer composition according to claim 1, further comprising a crosslinked polymer.
Expanded foam. 22. An olefinic polymer having a carboxylic acid function, a hydroxyl function, an amino function, an amide function or a combination of these functions as a side chain and an epoxy-functional silane, an amine function. 22. The expanded foam of claim 21 which is a reaction product with a crosslinker selected from the group consisting of silanes, organofunctional alkoxysilanes, titanates, multi-epoxy functional resins and amino crosslinkers. 23. The expanded foam of claim 21 wherein the crosslinked polymer is made using a free radical generating compound. 24. The free radical generating compound according to claim 22, which is an organic peroxide. 25. The free radical generating compound of claim 23, which is a polyazide functional compound. 26. The expanded foam of claim 9 wherein the second polyolefin has a melting point at least 10 ° C. below the melting point of the linear or modified linear polyolefin. 27. A soundproof panel comprising two skin layers and a foam sheet disposed between the skin layers, wherein the foam sheet is greater than 0.5 ASTM D1.
An expanded continuous tube having a sound absorption coefficient measured at 1,000 Hz according to 050 and consisting of at least one linear or modified linear polyolefin, wherein at least 50% of the cells are open and the average size of the cells is at least 1 mm A soundproof panel comprising a cellular polymer composition. 28. The composition of claim 27, wherein the composition has an airflow resistance of less than about 800,000 Rayls / m. 29. An ASTM D1050 of greater than 0.15
Consists of at least one linear or modified linear polyolefin having a sound absorption coefficient measured at 0 Hz and comprising an open cell polymer composition having at least 50% of cells open and having an average cell size of at least 1 mm. A foam sheet characterized by the above-mentioned. 30. The composition of claim 29, wherein the composition has an airflow resistance of less than about 800,000 Rayls / m.